Cho \(\mathop {\lim }\limits_{x \to 1} \frac{{{x^2} + ax + b}}{{{x^2} - 1}} = \frac{{ - 1}}{2}\quad \left( {a,b \in R} \right). Tổng \(S = {a^2} + {b^2}\) bằng

Câu hỏi :

Cho \(\mathop {\lim }\limits_{x \to 1} \frac{{{x^2} + ax + b}}{{{x^2} - 1}} = \frac{{ - 1}}{2}\quad \left( {a,b \in R} \right).\) Tổng \(S = {a^2} + {b^2}\) bằng